Conventionally, some of loudspeakers employ diaphragms formed of a resin material and additive. In general, polypropylene resin is adopted as the resin material. In this case, an inorganic filler such as mica is mixed as the additive to increase rigidity of the diaphragm. As for the additive, for example, berylium, aluminum, talc, calcium carbonate, and paper pulp can be used other than mica. To satisfy required characteristics of the diaphragm, one or more of them are preferably combined and added to the resin.
The diaphragm is fabricated using a general resin molding method. Consequently, the additive is dispersed in the resin.
Known patent literatures related to the present invention include PTL1 and PTL2.